飞机翼身接头疲劳试验件失效分析及其改进

Failure Analysis and Improvement Measures for Wing-fuselage Joint Fatigue Specimens

通过断口宏微观观察、金相组织检查、有限元数值分析、试验实施检查等方法,对某型飞机翼身接头疲劳试验件进行失效分析。结果表明:试验加载频率过快、左右加载作动筒不同步、试验件腹板约束不足,使得腹板连接螺栓处应力较大,从而出现疲劳裂纹,是导致试验件疲劳寿命较短的原因;断面放大可见大量的疲劳小弧线形貌,之后为快速裂纹扩展区,呈疲劳+韧窝形貌,因此,试验件断裂失效模式为典型的疲劳断裂。最后提出改进措施,提出合理的设计方案。

Failure analysis was performed on the wing-fuselage joint fatigue specimens of an aircraft through macro/micro observation, microstmcture examination, FEM analysis and fatigue tests. The results show that it is the higher load frequency, the asynchrony of the loads actuated by left and right cylinders and the insufficient constraints of web plate, that cause greater stress at the connecting bolt of the web, leading to the initiation of fatigue crack and the short fatigue life of the experimental samples. The amplification of fracture surface shows a large number of small fatigue curves and the fast crack propagation region shows the mixture feature of fatigue and dimples. Thus, the fracture failure mode is assumed to be the typical fatigue fracture. Finally, some improvement measures were put forward.